Water circulation power generation system for energy recovery

ABSTRACT

A water circulation power generation system for energy recovery includes at least one water circulation power generation system connected to a heat exchange system to obtain required water for a heat exchange process. The water circulation power generation system includes a water tank to store cooling water, a water supply pipeline and a recovery pipeline. The water supply pipeline draws water from the water tank to supply front end water to the heat exchange system. The recovery pipeline guides operational circulation water discharged from the heat exchange system and has a hydraulic power generator installed thereon driven by the operational circulation water to convert kinetic energy thereof to electric power. Thus during the operational circulation water flows to its recovery destination, its kinetic energy drives the hydraulic power generator to produce additional electric power.

FIELD OF THE INVENTION

The present invention relates to a water circulation power generationsystem for energy recovery and particularly to a power generation systemto recover kinetic energy of tail water of water circulation piping.

BACKGROUND OF THE INVENTION

With constant increasing of world population and widely use ofelectronic devices and development of transportation, global energyresources become extremely shortened. Many countries and institutionshave devoted huge amount of investments in developing alternativeenergy. At present, alternative energy is still constrained byproduction intensity and cannot fully meet requirements of consumers'habits. To substitute existing energy resources by extensive alternativeenergy still is far to reach.

However, there is still a lot of energy in people's life that can berecovered and reused. For instance, water circulation piping isinstalled in general buildings, the so-called process water or airconditioner cooling water, they all pass through a recovery pipeline inthe water circulation piping. Water is cleaned in the recovery pipelineand flowed back to the water circulation piping through the kineticenergy generated by elevation difference.

Take a commercial building as an example. The commercial buildingequipped with an air conditioning system or a cooling system generallyhas a heat exchange device at a higher floor (usually at the top floor),which is incorporated with a cooling water tower to draw water as themedium for heat exchange. The water discharged from the heat exchangedevice can be flowed back repeatedly to the heat exchange device andcooling water tower for cooling purpose.

Another example is a power generation plant (such as a nuclear powerplant) that requires huge amount of cooling water that often is drawnfrom seawater. The cooling water also goes through a heat exchangeprocess with used water (commonly called “tail water”) discharged to thesea by elevation difference (or with aid of pumps).

In the aforesaid conventional water circulation piping, mostly the tailwater in the recovery pipeline at the last section thereof canautomatically flow by elevation difference. The tail water has kineticenergy which is generated by automatic flowing and is not fully used inthe existing techniques. It is a waste of energy. There is still roomfor improvement especially in the age of increasing shortage of energyresources we are facing today.

SUMMARY OF THE INVENTION

In view of increasing shortage of global energy resources andgovernments and private institutions worldwide having devoted a greatdeal of investments in developing eco-friendly new energy resources ortrying to enhance equipment efficiency to provide sustainable benefitfor people now living and future generations, and with the urgent energyrequirement at present, to wait for new technology or another five orten years for building new power generation plants to fill in theexisting energy vacancy would be unrealistic. Hence the presentinvention aims to provide an energy recovery structure to utilize thekinetic energy generated by cooling water that is existed in the centralair conditioning of general commercial buildings or fire powergeneration plants constantly circulating back to its container torecover the unused energy without affecting the original circulationroute. Thus the invention not only can generate power also can minimizethe load of the power plants and reduce emission of carbon dioxide.

The present invention provides a water circulation power generationsystem for energy recovery including at least one water circulationpower generation system connected to a heat exchange system to obtainrequired water for heat exchange process. The water circulation powergeneration system includes a water tank to store cooling water, a watersupply pipeline and a recovery pipeline. The water supply pipeline drawswater from the water tank and supplies front end water to the heatexchange system. The recovery pipeline guides operational circulationwater discharged from the heat exchange system, and has a hydraulicpower generator installed thereon driven by the operational circulationwater to convert kinetic energy of the operational circulation water toelectric power.

Thus during the operational circulation water flows to a recoverydestination, its kinetic energy can drive the hydraulic power generatorto generate additional electric power. It can save a lot of powerconsumption in a long-term use, and also achieve long-term goals ofenergy saving and carbon reduction and ecological developmentmaintenance now pursued by governments worldwide.

The foregoing, as well as additional objects, features and advantages ofthe invention will be more readily apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the invention adapted to a conventionalcooling water tower.

FIG. 2 is a schematic view of an embodiment of the invention adapted toa cooling water tower of a commercial building.

FIG. 3 is a schematic view of the invention adapted to a refrigerationset of a conventional industrial and general building.

FIG. 4 is a schematic view of an embodiment of the invention adapted toa cooling water tower of a nuclear power plant.

FIG. 5 is a schematic view of an embodiment of the invention adapted toa nuclear power plant with the cooling water discharged directly

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention aims to provide a water circulation powergeneration system for energy recovery including at least one watercirculation power generation system connected to a heat exchange systemto obtain water needed for heat exchange process. Referring to FIG. 1,the water circulation power generation system includes a water tank 1 tostore cooling water, a water supply pipeline 2 and a recovery pipeline4. The heat exchange system 3 is connected to the water supply pipeline2 and recovery pipeline 4. The water supply pipeline 2 includes at leastone water drawing pump 21, a water stop valve 22 and a check valve 23.The water drawing pump 21 draws water from the water tank 1 and suppliesfront end water to the heat exchange system 3. The check valve 23prevents the water from flowing back to the water tank 1. The water stopvalve 22 closes the water supply pipeline 2 during repairing orreplacing the pipeline. The front end water supplied to the heatexchange system 3 serves as a medium for heat exchange. The heatexchange system 3 can be implemented in many types. FIG. 1 illustratesone of the possible types that includes a set of radiation fins 31, acooling water tower 32 and a fan 33. The radiation fins 31 are directlyin contact with the front end water to exchange heat. The water passedthrough the radiation fins 31 flows to the cooling water tower 32 whichhas the fan 33 installed on the surrounding thereof. The fan 33generates airflow to carry the heat away. The water discharged from thecooling water tower 32 is defined as operational circulation water afterfinishing the heat exchange process of the heat exchange system 3. Therecovery pipeline 4 guides the operational circulation water dischargedfrom the heat exchange system 3, and has a hydraulic power generator 41installed thereon driven by the operational circulation water andanother water stop valve 42. The hydraulic power generator 41 is drivenby the operational circulation water to convert kinetic energy of theoperational circulation water to electric power. The operationalcirculation water guided by the recovery pipeline 4 can be guided backagain to the water tank 1 to be reused for the heat exchange system 3.The water circulation power generation system further includes abranched backup pipeline 5 communicating with the recovery pipeline 4.The backup pipeline 5 also has a water stop valve 51. As the recoverypipeline 4 and hydraulic power generator 41 require periodical repairand maintenance, the recovery pipeline 4 and backup pipeline 5 can bealternately used when necessary. In regular conditions, the water stopvalve 42 of the recovery pipeline 4 is opened to let the operationalcirculation water to pass through the hydraulic power generator 41,while the water stop valve 51 of the backup pipeline 5 is closed. Duringrepair and maintenance of the hydraulic power generator 41, the waterstop valve 42 is closed and another water stop valve 51 is opened to letthe operational circulation water to pass through the backup pipeline 5.By means of the technique set forth above, the kinetic energy of theoperational circulation water can drive the hydraulic power generator 41to generate electric power to produce additional power. After long-termuse, a lot of extra electric power can be produced, and long-term goalsof extra energy production and carbon reduction and ecologicaldevelopment maintenance now pursued by governments worldwide can also beachieved.

Referring to FIG. 2, the water circulation power generation systempreviously discussed can be installed in an air conditioning system of abuilding. Take a building with twenty floors on the ground and threefloors underground as an example. Assumed the building has a chill watermachine set (heat exchange system 3) with a capacity of 750 tons servingas the central air conditioning system. If a water tank is located in amachine room at the third floor underground, and each floor has anaverage height of three meters.

The height from the underground water tank to the top floor is: 23×3m=69 m

The water required by the cooling water tower of the chill water machineset is: 750 t×0.0002 m³/s=0.15 m³/s (1 ton requires about 0.0002 m³/s ofwater).

The capacity of the water drawing pump 2 supplying water to the coolingwater tower is:

0.15 m³/s×69 m×9.81×1000 kg/m³/0.8=127 KW

The estimated recovery energy of the hydraulic power generator 41 is:

0.15 m³/s×69 m×9.81×1000 kg/m³×0.8=81 KW

Assumed the chill water machine set consumes average NT $3/KWh inoperating 24 hours every day, the energy recovery saved everyday is:

81 KW×24 hours×NT$3/KWh=NT$5832 (about USD$180)

Please refer to FIG. 3. It includes a refrigeration set 312 whichcontains a condenser 310 and an evaporator 311. The evaporator 311obtains water from a chill water tank 1 a through a chill water drawingpump 21 a. The condenser 310 obtains water from a cooling water tank 1 bthrough a cooling water drawing pump 21 b. The water circulation powergeneration system is connected to a rear end of the condenser 310 orevaporator 311, or the condenser 310 and evaporator 311 are connectedrespectively to a water circulation power generation system as shown inFIG. 3. The evaporator 311 guides the operational circulation water backto the chill water tank 1 a through the recovery pipeline 4. The chillwater tank 1 a can include a chill water supply pump 6 supplying chillwater to plant facilities or air conditioning equipment of the building.The water discharged from the condenser 310 first flows to the coolingwater tower 32 to be cooled by the fan 33, then the operationalcirculation water is guided back to the cooling water tank 1 b throughanother recovery pipeline 4. Both of the recovery pipelines 4 havehydraulic power generators 41 installed thereon to improve utilizationof the kinetic energy of the operational circulation water.

Referring to FIG. 4, the heat exchange system 3 and water circulationpower generation system can be installed in a power plant, and a nuclearpower plant is taken as an example in this embodiment. Water in thewater tank 1 is supplied to the heat exchange system 3 through the waterdrawing pump 21 and the water supply pipeline 2. In an embodiment shownin FIG. 4, the heat exchange system 3 includes a condenser 34 and acooling water tower 35. The condenser 34 contains condensed water whichis sent to a nuclear reactor 7 through a condensed water pump 341. Thecondensed water is evaporated into steam in the nuclear reactor 7 todrive a steam turbine 71 and a power generator 72 to generate electricpower. The electric power is distributed through a power distributionstation 73. The steam passing through the steam turbine 71 returns tothe condenser 34 to be condensed into water again. The front end waterprovided by the water supply pipeline 2 is used to exchange heat in thecondenser 34. The water passes through the condenser 34 and is cooled inthe cooling water tower 35, then the water is sent back to the watertank 1. The hydraulic power generator 41 is located on the recoverypipeline 4 between the cooling water tower 35 and water tank 1 torecover the kinetic energy of the operational circulation water.

Refer to FIG. 5 for another embodiment with a nuclear power plant as anexample. The operational circulation water passing through the condenser34 may also be directly discharged to the sea through the recoverypipeline 4 as shown in FIG. 5, and the kinetic energy of the operationalcirculation water is recovered by the hydraulic power generator 41before discharging to the sea.

Take Chinshan nuclear power plant in Taiwan as an example. It has twosteam turbine generators, each has a capacity of 636 Mw thus total is1272 Mw. Assumed that the discharge temperature difference is set at 10°C., the cooling water amount required for each steam turbine generatoris:

GMP=14295×636 Mw/18 F (10° C.)=505090 gpm=31.9 m³/sec

If the water pressure at the distal end of the pipeline is 1 kg/cm², andthe height of the water head is about 10 m, the estimated recoveryenergy is:

Water amount×water head height×9.81×efficiency×density=31.9 m³/sec×10m×9.81 m/s/s×0.8×1000 kg/m³=2503 KW

Assumed that operating 24 hours a day with average consumption ofNT$3/KWh, the energy recovery saved everyday is: 2503 KW×24hours×3=NT$180216 (about USD $5600)

The above estimate shows merely the direct energy recovery yield,additional potential yield of carbon discharge (carbon dioxide trade) issaved:

The coal-fired power generation has carbon discharge of 2.095 lbs/KWh,oil-fueled power generation has carbon discharge of 1.969 lbs/KWh, andgas/natural gas-fueled power generation has carbon discharge of 1.321lbs/KWh. Thus the average of the three above mentioned power generationways has carbon discharge of 1.795 lbs/KWh.

Thus the carbon discharge converted from the alternate power plantcarbon emission is: 1.795×2503 KWh/2200 lbs=2.04 tons

Assumed that the exchange price of carbon dioxide is NT$ 331/ton, theadditional yield is NT$16206 (about USD$500) per day.

While FIGS. 4 and 5 illustrate an embodiment with a nuclear power plant,the technique proposed by the invention can also be adapted to a thermalpower plant by capturing the operational circulation water in the watercirculation power generation system to generate electric power. Variousoperation types of the power plants also can be included in theinvention.

In short, the present invention can save or recover a great deal ofpower in the long run, and achieve long-term goals of energy recoveryand carbon reduction and ecological development maintenance now pursuedby governments worldwide.

While the invention has been described by means of specific embodiments,numerous modifications and variations could be made thereto by thoseskilled in the art without departing from the scope and spirit of theinvention set forth in the claims.

In summation of the above description, the present invention provides asignificant improvement over the conventional techniques and complieswith the patent application requirements, and is submitted for reviewand granting of the commensurate patent rights.

1. A water circulation power generation system for energy recoveryincluding at least one water circulation power generation systemconnected to a heat exchange system to obtain water required for a heatexchange process, the water circulation power generation systemcomprising: a water tank to store cooling water; a water supply pipelinewhich draws water from the water tank and supplies front end water tothe heat exchange system; and a recovery pipeline which guidesoperational circulation water discharged from the heat exchange systemand includes a hydraulic power generator driven by the operationalcirculation water to convert kinetic energy thereof to electric power.2. The water circulation power generation system of claim 1, wherein thewater supply pipeline includes at least one water drawing pump, a waterstop valve and a check valve.
 3. The water circulation power generationsystem of claim 1 further including a branched backup pipelinecommunicating with the recovery pipeline.
 4. The water circulation powergeneration system of claim 3, wherein the recovery pipeline and thebackup pipeline include respectively a water stop valve.
 5. The watercirculation power generation system of claim 1, wherein the heatexchange system includes a condenser and an evaporator, the watercirculation power generation system being connected to the condenser orthe evaporator.
 6. The water circulation power generation system ofclaim 1, wherein the heat exchange system includes a condenser and anevaporator that are connected respectively to one water circulationpower generation system.
 7. The water circulation power generationsystem of claim 1, wherein the heat exchange system is located in an airconditioning system of a building.
 8. The water circulation powergeneration system of claim 1, wherein the heat exchange system islocated in a power plant.